Mark supervised profiles as such immediately when they're created.

chrome/browser/profiles/profile.h

Index: chrome/browser/profiles/profile.h
diff --git a/chrome/browser/profiles/profile.h b/chrome/browser/profiles/profile.h
index 3af9eeb3c6176af068cef908cb168cc99dd79ed1..c0fcb62d1ad9ba9ee68d4717394fc42628e21baa 100644
--- a/chrome/browser/profiles/profile.h
+++ b/chrome/browser/profiles/profile.h
@@ -134,6 +134,10 @@ class Profile : public content::BrowserContext {
    public:
     virtual ~Delegate();
 
+    // Called when preferences for the profile have been loaded, but before all
+    // the profile services have been initialized.
+    virtual void OnPrefsLoaded(Profile* profile) = 0;
+
     // Called when creation of the profile is finished.
     virtual void OnProfileCreated(Profile* profile,
                                   bool success,